Code Division Multiple Access (CDMA) is one of the more recently developed radio technologies competing in the cellular/microcellular and Personal Communication Services (PCS) market arenas. CDMA has the advantage of providing approximately double the coverage area in comparison to standard Global Systems for Mobile Communications (GSM), which are Time Division Multiple Access (TDMA) based. The majority of PCS providers are therefore moving toward CDMA system development and deployment.
The first step in designing a CDMA system is to identify a technique for determining cell size. As is readily apparent, larger cells provide for a more economical system. At this time, however, there is no standard technique for cell design in a CDMA system. It is well recognized by those of ordinary skill in the art, however, that a number of parameters affect such cell design including the radio frequency (RF) employed (e.g., 800 MHz or 1800 MHz), Frame Error Rate (FER), traffic loading, signal level, terrain between the base station and the mobile location, surface cover (i.e., urban, suburban, rural, etc.) between the base station and the mobile location, and voice quality.
A number of prior art methods and systems exist for use in such cell design, such as the method disclosed by A. Gamst et al. in "Cellular Radio Network Planning", IEEE AES Magazine, February, 1986.
However, the Generalized Radio Network Design (GRAND) technique discussed therein, as well as other prior art cellular communication planning tools, such as that disclosed in U.S. Pat. No. 5,293,640 issued to Gunmar et al., are directed to optimizing a cellular system with respect to frequency to accommodate a certain traffic demand, or to determining the effect of different antenna patterns on propagation.
As a result, such prior art methods and systems fail to strictly or accurately define coverage areas and cell boundaries. Thus, there is a need for an improved method and system for designing a cell in a CDMA communication system and the like, such as GSM or other TDMA based systems. Such an improved method and system would, of course, account for the well known parameters associated with such cell design, with emphasis on those parameters having the most importance to proper operation of the communication system, particularly signal level, error rate and voice quality.
More particularly, such a method and system would combine measured field data in a CDMA system or the like representing error rate and voice quality as a function of signal level. From such relations, the signal level for a desired error rate and voice quality level can be determined given the prevailing environmental conditions, including terrain and surface cover (i.e., urban, suburban, rural, etc.). In contrast to the prior art, however, such an improved method and system would provide for accurate determination of coverage areas and cell boundaries for the desired signal level.